QoS for SIP on Cisco Router (1841)

Hello All!

We have some hosted PBX customers that have been experiencing  voice quality issues while using cable and DSL circuits.  We need to get some type of QoS configured on the edge device and/or phones themselves.  We need keep voice traffic as priority to keep voice quality high during high circuit utilization.  

Here is a typical setup:

- Cisco 1800 series router (mostly 1841's) as the edge device
- VPN from customer site to our VPN concentrator
- Grandstream GXP2100 phones

Any ideas?
Good tricks for Cisco router to handle QoS well?
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Is the issue on your side is network saturation?

Your issue might be on the inbound which a QoS on your side might not be managed.
Sandeep GuptaConsultantCommented:
Would you mind to share configuration of your router?

Generally you can set auto-qos in secured VPNs.
FrankkadafAuthor Commented:
Here's a general configuration of our routers. Some of them have additional IPSEC transport mode configuration (no left/right subnets) which shouldn't make a difference, traffic is still going over a GRE tunnel.
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If your voice travelers through VPN, you would prioritize VPN traffic and within the VPN prioritize VOIP/sip/voice traffic.
FrankkadafAuthor Commented:
Our issue is we cannot control ingress traffic. We want to shape ingress traffic as some cases clients will be downloading files and it will cause poor voice quality.
You can control what is leaving your network or entering, by prioritizing specific traffic such that VOIP/SIP will have a higher priority while other traffic will be "dropped"

Rate-limiting might be another way to control network use. I.e. A fileserver can only transmit at max rate of 10% of available bandwidth, etc.

QoS can be managed within to a point. Once the traffic leaves your network, there is nothing you can do.
FrankkadafAuthor Commented:
We've tried prioritizing tunnel traffic (GRE going out our WAN interface) but there are still some problems, such as when customers perform multiple concurrent downloads (i.e. Windows updates all firing at once). In that sort of case, the amount of downstream traffic causes voice quality issues due to high latency and bandwidth utilization. We want to find some way to limit the incoming traffic.
It is a multi-tiered Qos
The issue is that I am unclear where or how your VOICE travels
if all goes via VPN, then you will prioritize the VPN
wihtin the VPN you will prioritize VOICE
you would rate limit HTTP/ftp/streaming if not deny them.

I think I had this discussion recently in another question, that dealt with being able to apply QoS on one direction only.
Usually, the incoming is separate from outgoing the bandwidth available for incoming might be larger than outgoing (Asynchronous 1.5MB inbound/768 outgoing) versus synchronous meaning you have the same rate inbound as outbound.

An option for updates etc. might be to setup an internal WSUS server and manage its download on a schedule/approval.
FrankkadafAuthor Commented:
How would we prioritize any traffic to/from a particular IP address? We want to set it up so it will prioritize queuing packets for the VPN concentrator and drop anything else.
You would not prioritize base on IP destination, but based on the packet type.


Your best bet is to check cisco.com for various examples.

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